BEIJING (AP) -- An exiled Chinese democracy campaigner who left New York to return to China has disappeared and is believed to be in police detention, a rights group and U.S.-based Chinese exiles said today.

Zhou Yongjun, who as a university student helped lead the 1989 democracy demonstrations in Tiananmen Square, made hasty calls on Dec. 21 to a friend and his wife in New York, saying police were about to arrest him and he needed a lawyer, the Information Center of Human Rights and Democratic Movement in China said.

Friends and family did not know where he was calling from and have not heard from him since, the Hong Kong-based group said.

Zhou had traveled to Hong Kong and was refused entry into the rest of China at the border city of Shenzhen on Dec. 17, the group said. It added he then talked to friends in Hong Kong about sneaking into China.

Zhou wanted to do business in China and see his parents in southwestern Sichuan province, it said.

China's Foreign Ministry did not immediately answer a telephoned question about Zhou's whereabouts.

Chinese authorities are believed to have a ``black list'' of overseas-based dissidents and foreigners to be barred from China because of their political activities.

Police seized three exiled democracy campaigners who tried to sneak into China during the fall. One faces trial on a subversion charge, and the others were sentenced without trial to forced labor.

Zhou, 31, was imprisoned for two years after the 1989 democracy movement was violently suppressed by the military, the Hong Kong group said.

He kept a low profile since he moved to the United States in 1993 and began to publish a Chinese magazine, according to a statement from the Free China Movement, a Washington-based lobbying group of Chinese exiles.

It said he may have been detained because he was interested in publishing a book by a Chinese dissident poet who also lives in exile in New York, Huang Xiang.